Ultrasonic Gelling of Channelized 2:1 Clay in Ionic Media

Abstract

Ultrasonic energy was used to disperse and gel dry suspending clays in ionic fertilizer media. The method used involved bringing a mixture of fluid fertilizer and clay into contact with ultrasonic energy generated by either a piezoelectric or magnetostrictive transducer. The channelized 2:1 clays (attapulgite and sepiolite) were effectively gelled at a frequency of 20,000 Hz and a power density of about 2 watts per milliliter. The ultrasonic energy reduced the crystal agglomerates that make up the clay particles into their individual needlelike crystals. The dispersed clay crystals then formed a latticework capable of suspending solid particulates of up to about 20 mesh (850 micrometers) in size. A comparative study of mechanical shear (provided by a Waring blender) and ultrasonic methods of dispersing and gelling clays to produce ionic suspensions showed that ultrasonically induced gelation was more efficient, resulting in suspensions of equal or superior quality and with less energy consumption.